Daughters of men who are overweight could be more likely to develop breast cancer, new research suggests.
A study of mice found that obesity can change the genes in a father's sperm, which results in the delayed development of their daughter's breast tissue - and can eventually lead to cancer.
One of the study's lead authors, Sonia de Assis, said: "Of course our study was done in mice, but it recapitulates recent findings in humans which show that obese men have significant epigenetic alterations in their sperm compared to lean men."
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Peter Dazeley via Getty Images
This is one of the first animal studies to investigate a link between paternal obesity and breast cancer in offspring.
Obese male mice and normal weight female mice produce female offspring that are overweight at birth. This results in delayed development of their offspring's breast tissue and increased rates of breast cancer, scientists said.
Epigenetic regulators can switch genes on or off. They enable external or environmental factors - such as the effects of a person's lifestyle - to be passed on to offspring.
Gene expression is the process by which specific genes are activated to produce a required protein.
Researchers believe miRNAs may carry epigenetic information from obese dads to their daughters.
According to scientists, these miRNAs can affect alterations in body weight and other molecular pathways linked to cancer development.
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Breast Cancer Signs And Treatment
What Are The Symptoms?(01 of10)
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"A new painless, firm breast lump with irregular margins is a potential symptom of breast cancer," says Dr. Sandhya Pruthi, a breast cancer researcher at the Mayo Clinic. "The cancer diagnosis is confirmed following a biopsy of the lump." She notes that usually, women who are newly diagnosed with breast cancer are healthy and don't feel sick at all. (credit:LarsZahnerPhotography via Getty Images)
Other Symptoms(02 of10)
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Another potential symptom/sign of breast cancer, Pruthi notes, is a new onset of persistent redness on the skin overtop the breast with an orange peel appearance. This would also need a biopsy to confirm a diagnosis of breast cancer. (credit:Image Source via Getty Images)
Metastatic Cancer Symptoms(03 of10)
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"If the cancer is very advanced (metastatic) then the symptoms may also include weight loss, bone pain, headaches, nausea and persistent cough," Pruthi says. (credit:pamela burley via Getty Images)
What Are The Risk Factors?(04 of10)
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Some commonly associated risk factors, Pruthi says, are menstruation before age 11, menstruation after age 54, a first pregnancy after age 35 and a family history of relatives diagnosed with breast or ovarian cancer. (credit:AP Photo/M. Spencer Green)
Are There Any Lifestyle Risk Factors?(05 of10)
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"There is evidence in the literature that obesity after menopause, lack of regular exercise, consuming greater than more or more alcoholic beverages daily, and a high fat diet can all be associated with a higher breast cancer risk," Pruthi notes. But, she points out, "women need to know that any woman can get breast cancer even in the absence of any of these risk factors." (credit:Adrian Samson via Getty Images)
Can I Eat Anything To Prevent It?(06 of10)
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There are no specific types of diets, Pruthi says, but rather women are encouraged to eat fruits, vegetables, fibre, and minimize their alcohol and fat intake, as well as get regular exercise. (credit:lola1960 via Getty Images)
How Do Doctors Determine Treatment?(07 of10)
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"The most current treatment of breast cancer has taken on a individualized approach and is dependent on the biology or aggressive features of the breast cancer," Pruthi explains. "Breast cancer is a heterogeneous disease and this means that are many sub-types and different degrees of aggressiveness. So staging, which typically takes into account common prognostic features such as tumour size and if lymph nodes are involved, are no longer the only factors doctors use to determine treatment options." (credit:Christopher Futcher via Getty Images)
So What Do They Look At?(08 of10)
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"Today the biology of the tumour is also characterized by molecular markers (also known as predictive markers) such as if the estrogen or progesterone receptor is positive or negative and if the HER 2 protein is positive or negative," she says. "This helps decide who will benefit from a specific chemotherapy regimen, hormonal medications known as antiestrogens or who may need both chemotherapy and hormonal treatment." (credit:BluePlanetEarth via Getty Images)
What About Preventative Mastectomies?(09 of10)
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"Preventive mastectomy is an option for women at very high risk for developing breast cancer because they are BRCA 1 or 2 gene positive or if someone has hereditary predisposition to getting breast cancer but chooses not to have the genetic testing done," Pruthi says. "It is prudent that women who are considering this surgery know their family history in detail. Based on the moderate or strong family history, your doctor would recommend you meet with a genetic counselor to go over the family pedigree and help decide who should test for the breast cancer gene, when to test and how to interpret the genetic test results before proceeding with this preventive surgery." (credit:Jesús Jaime Mota via Getty Images)
Are Other Preventative Treatments Available?(10 of10)
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"High risk women who have had precancerous breast biopsies or strong family history may also be eligible to take preventive medications such as tamoxifen, raloxifene or exemestane to reduce breast cancer risk," Pruthi adds. (credit:art-4-art via Getty Images)
"This study provides evidence that, in animals, a fathers’ body weight at the time of conception affects both their daughters’ body weight both at birth and in childhood as well as their risk of breast cancer later in life," said Sonia de Assis, an assistant professor in the department of oncology at Georgetown Lombardi.
"Of course our study was done in mice, but it recapitulates recent findings in humans which show that obese men have significant epigenetic alterations in their sperm compared to lean men.
"Our animal study suggests that those epigenetic alterations in sperm may have consequences for next generation cancer risk."
The next step is to see if the same associations regarding breast cancer risk hold for daughters of human fathers who are overweight around the time of conception.
de Assis added: "Until we know about this association in men, we should stick to what we all know is good advice: women — and men — should eat a balanced diet, keep a healthy body weight and life-style not only for their own benefit but also to give their offspring’s the best chances of being healthy."